1. Field of the Invention:
This invention relates to and has among its objects the provision of novel apparatus for planting seeds. Further objects of the invention will be evident from the following description.
2. Description of the Prior Art:
The general method of planting seeds involves digging a furrow or large hole in the soil, placing the seeds in the opening, and covering the seeds with soil. Oftentimes, however, seedlings fail to emerge because of premature soil drying, accumulation of salts in the shallow seedbeds, or inability to break through even weak soil crusts. To insure adequate stands of certain crops, therefore, excess seed is planted. One problem is that the crop which results must be thinned, a time-consuming and expensive operation.
A solution to the above problem involves dropping a seed into a small hole and leaving the seed uncovered. This process is known as the punch (or dibble) planting method and allows precision planting of crops. The air in the small hole, which contains the seed, remains reasonably stable and the soil does not dry out. This results because of the natural soil temperature gradients occuring during the day. The seed germinates and sends its growing tip to the surface without resistance from soil particles. Also, seeds may be planted at a deeper level in the punch method. This places the seeds below the zone of high salt accumulation at the surface. Further, the depth of the seed within the hole is at a level where moisture conditions remain optimum for seed germination for a longer period.
Experimental machines for punch planting are described in Transactions of the ASAE, Vol. 16, No. 4, pp 656-659 (1973). Two types of machines are discussed--a pneumatic punch planter and a belt-type punch planter. Neither machine has advanced beyond the experimental stage to commercial use because of certain inherent defects. In the pneumatic planter forward speeds are too slow for practical operation. The pneumatic planting machine can operate at a maximum speed of one mph., whereas efficient planting requires a speed of at least three mph. If the pneumatic planting device is operated at speeds greater than one mph., the hole is misformed and seeds are scattered. The belt-type planter is ineffective because of belt slippage with respect to the soil surface, which causes the seeds to be misplaced.